CN112332380B - Intelligent judgment and processing method for multiple earth faults of power distribution network - Google Patents

Intelligent judgment and processing method for multiple earth faults of power distribution network Download PDF

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CN112332380B
CN112332380B CN201910653726.8A CN201910653726A CN112332380B CN 112332380 B CN112332380 B CN 112332380B CN 201910653726 A CN201910653726 A CN 201910653726A CN 112332380 B CN112332380 B CN 112332380B
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fault
distribution network
power distribution
earth fault
line
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李景禄
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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
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • 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
    • G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors
    • 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
    • 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

Abstract

A power distribution network multiple earth fault intelligent judgment and processing method is characterized in that an earth fault processing device judges that a power distribution network has a permanent earth fault, when an earth fault line is selected, the fault line is not cut off, the device is not reset, and the earth fault continues, the change of a power distribution network fault characteristic parameter is detected again, whether multiple earth is generated is judged according to the change of the fault characteristic parameter, a subsequent earth line is selected, and when the fault line is cut off, the fault characteristic parameter is detected, and the multiple earth fault is judged and processed.

Description

Intelligent judgment and processing method for multiple earth faults of power distribution network
Technical Field
The invention relates to the field of single-phase earth fault processing of a power distribution network, and provides intelligent judgment and processing of multiple single-phase earth faults of the power distribution network.
Background
When single-phase earth faults of the power distribution network are processed by the earth fault processing device in thunderstorm weather in the south, the single-phase earth faults are not removed, when the faults are continuous, multiple single-phase earth faults of the power distribution network can occur, after fault lines are selected, the fault lines can not be removed in time due to various reasons, and multiple earth faults of the power distribution network occur again during the fault continuous period, so that the earth fault processing device can be influenced for judging and processing the properties of the earth faults. If multiple earth faults cannot be judged and processed correctly, not only can the power supply reliability be influenced, but also the personal safety and the power grid safety can be endangered due to the expansion of accidents in serious cases.
The existing ground fault processing device can only process a single ground fault, because when the ground fault is continuous, the fault characteristic parameter changes unobvious, and the ground fault processing device cannot identify the change caused by multiple ground faults which occur again in the continuous period of the ground fault from the ground fault characteristic parameter, so that the existing ground fault processing device cannot identify and process the multiple ground faults which occur again in the continuous period of the ground fault.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides an intelligent judgment and processing method for multiple earth faults of a power distribution network. Judging that the power distribution network has permanent high-resistance earth fault in the earth fault processing device, when an earth fault line is selected, the fault line is not cut off, the device is not reset, and during the earth fault duration, detecting that the neutral point displacement voltage of the power distribution network has stable increment delta U againNNot less than delta, and an increment delta i for generating stable zero sequence current in a feeder line0When the resistance to earth ground fault of the fault point of the subsequent fault is less than earth ground resistanceThe impedance to ground of the previous fault point, the subsequent fault is the same-name phase fault, and the subsequent fault line is a line with stable increment of zero-sequence current; if the displacement voltage of the neutral point of the power distribution network is stabilized and increased by delta UN<Delta, but the zero sequence current in the other feeder is a stable increment Δ i0And xi, judging that the power distribution network has the same-name phase high-resistance grounding fault again, or judging that the subsequent fault is the different-name phase high-resistance grounding fault, and judging that the line of the subsequent fault is a line with the stable increment of the zero-sequence current.
The method comprises the steps that a ground fault processing device judges that a permanent low-resistance ground fault occurs in the power distribution network, when a ground fault line is selected, the fault line is not cut off, the device is not reset, during the duration of the ground fault, the displacement voltage of a neutral point of the power distribution network is unchanged, and the stable increment delta i of zero-sequence current in a feeder line is detected again0And xi, judging that the single-phase earth fault occurs again in the power distribution network in the period, wherein the subsequent fault is a same-name-phase low-resistance earth fault or a different-name-phase high-resistance earth fault, and the line of the subsequent fault is a line with stable increment of zero-sequence current.
After the earth fault processing device judges that the power distribution network has permanent high-resistance earth fault, the single-phase earth fault characteristics of the power distribution network still conform to delta U after the earth fault line is cut offN≥δ、Δi0When the voltage is more than or equal to xi, the single-phase earth fault still exists in the power distribution network, the fault needs to be processed continuously, the processing is carried out according to different processing methods of the earth fault processing device until the fault is recovered, and the device is reset after the earth fault is recovered.
The earth fault processing device judges that the power distribution network has a permanent low-resistance earth fault, and after an earth fault circuit is cut off, the neutral point displacement voltage stability increment of the power distribution network conforms to the following conditions: delta UNIs not less than delta, and the increment delta i of the zero sequence current of any line0And when the zero sequence current is larger than or equal to xi, indicating that a fault line still grounded in the power distribution network is still present, continuously processing and cutting off the line with the maximum zero sequence current until the zero sequence current reaches delta UN<Delta, increment of zero sequence current in each feeder line, delta i0<ξ。
Delta is an absolute increment value of the neutral point displacement voltage when the power grid has a ground fault, and the absolute value of delta is set according to the requirement of high-resistance grounding starting sensitivity and is larger than the change of the neutral point displacement voltage of the power grid caused by the voltage fluctuation of the power grid; xi is an increment standard value of the stable zero sequence current in the line when the earth fault occurs in the power distribution network, the value is set according to the detection sensitivity of high-resistance earth, the homonymy earth fault is a single-phase earth fault of different lines but the same phase, and the heteronymy earth fault is a single-phase earth fault of different lines and different phases.
The single-phase high-resistance earth fault and the single-phase low-resistance earth fault are divided by neutral point displacement voltage when U is usedN<UGLWhen it is a single-phase high-resistance earth fault, when UN≥UGLTime, single-phase low-resistance earth fault, UGLThe boundary value of the high-resistance earth fault and the low-resistance earth fault is 50% of the phase voltage.
The invention has the following advantages:
1. the method judges whether the power distribution network is subjected to multiple grounding again in the fault duration by detecting the change of the fault characteristic parameters in the fault duration, so that the fault line can be conveniently identified, the fault handling capacity of the power distribution network is improved, and particularly the accuracy of the grounding line selection of the multiple grounding of the power distribution network is improved.
2. After the earth fault line is cut off, the method continues to detect the fault characteristic parameters until the fault processing is finished, and is easy to implement and strong in operability.
Detailed Description
Judging that the power distribution network has permanent high-resistance earth fault in the earth fault processing device, when an earth fault line is selected, the fault line is not cut off, the device is not reset, and during the earth fault duration, detecting that the neutral point displacement voltage of the power distribution network has stable increment delta U againNNot less than delta, and a stable increment delta i of zero sequence current in the feeder line0When the voltage of the power distribution network is greater than xi, the situation that the single-phase earth fault occurs in the power distribution network in the period is judged, the earth impedance of the fault point of the subsequent fault is smaller than the earth impedance of the previous fault point, the subsequent fault is the same-name phase fault, and the subsequent fault line is a line with stable increment of zero-sequence current; if the displacement voltage of the neutral point of the power distribution network is stabilized and increased by deltaUN<Delta, but the zero sequence current in the other feeder is a stable increment Δ i0And xi, judging that the power distribution network has the same-name phase high-resistance grounding fault again, or judging that the subsequent fault is the different-name phase high-resistance grounding fault, and judging that the line of the subsequent fault is the line with the stable increment of the zero-sequence current.
The method comprises the steps of judging whether a permanent low-resistance earth fault occurs in the power distribution network in an earth fault processing device, selecting an earth fault line, enabling the fault line not to be cut off and the device not to be reset, enabling the neutral point displacement voltage of the power distribution network to be unchanged during the duration of the earth fault, and detecting that the zero sequence current in the feeder line has a stable increment delta i again0And xi, judging that the single-phase earth fault occurs again in the power distribution network in the period, wherein the subsequent fault is a same-name-phase low-resistance earth fault or a different-name-phase high-resistance earth fault, and the line of the subsequent fault is a line with stable increment of zero-sequence current.
After the earth fault processing device judges that the power distribution network has permanent high-resistance earth fault, the single-phase earth fault characteristics of the power distribution network still conform to delta U after the earth fault line is cut offN≥δ、Δi0When the voltage is more than or equal to xi, the single-phase earth fault still exists in the power distribution network, the fault needs to be processed continuously, the processing is carried out according to different processing methods of the earth fault processing device until the fault is recovered, and the device is reset after the earth fault is recovered.
The earth fault processing device judges that the power distribution network has a permanent low-resistance earth fault, and after an earth fault circuit is cut off, the neutral point displacement voltage stability increment of the power distribution network conforms to the following conditions: delta UNIs not less than delta, and the increment delta i of the zero sequence current of any line0And when the zero sequence current is larger than or equal to xi, indicating that a fault line still grounded in the power distribution network is still present, continuously processing and cutting off the line with the maximum zero sequence current until the zero sequence current reaches delta UN<Delta, increment of zero sequence current in each feeder line, delta i0<ξ。
Delta is an absolute increment value of the neutral point displacement voltage when the power grid has a ground fault, and the absolute value of delta is set according to the requirement of high-resistance grounding starting sensitivity and is larger than the change of the neutral point displacement voltage of the power grid caused by the voltage fluctuation of the power grid; xi is an increment standard value for stabilizing zero sequence current in the line when the power distribution network has an earth fault, the value is set according to the detection sensitivity of high-resistance grounding, the homonymy phase grounding fault is a single-phase grounding fault of different lines but the same phase, and the heteronymy phase grounding fault is a single-phase grounding fault of different lines and different phases.
The single-phase high-resistance earth fault and the single-phase low-resistance earth fault are divided by neutral point displacement voltage when U is usedN<UGLWhen it is a single-phase high-resistance earth fault, when UN≥UGLTime, single-phase low-resistance earth fault, UGLThe boundary value of the high-resistance earth fault and the low-resistance earth fault is 50% of the phase voltage.
The above description is only a preferred embodiment of the present invention, and the scope of the present invention is not limited to the above embodiments, and all technical solutions that belong to the idea of the present invention belong to the scope of the present invention. It should be noted that several modifications and adaptations to those skilled in the art without departing from the principles of the present invention should also be considered within the scope of the present invention.

Claims (2)

1. A power distribution network multiple earth fault intelligent judgment and processing method is characterized in that: judging that the power distribution network has permanent high-resistance earth fault in the earth fault processing device, when an earth fault line is selected, the fault line is not cut off, the device is not reset, and during the earth fault duration, detecting that the neutral point displacement voltage of the power distribution network has stable increment delta U againNNot less than delta, and a stable increment delta i of zero sequence current in the feeder line0When the voltage of the power distribution network is greater than xi, the situation that the single-phase earth fault occurs in the power distribution network in the period is judged, the earth impedance of the fault point of the subsequent fault is smaller than the earth impedance of the previous fault point, the subsequent fault is the same-name phase fault, and the subsequent fault line is a line with stable increment of zero-sequence current; if the displacement voltage of the neutral point of the power distribution network is stabilized and increased by delta UN<Delta, but the zero sequence current in the other feeder is a stable increment Δ i0And when the current value is more than or equal to xi, judging that the same-name-phase high-resistance grounding fault occurs again in the power distribution network, or the subsequent fault is a different-name-phase high-resistance grounding fault, and the line of the subsequent fault is a zero-sequence current generatorGenerating a line of stable increments;
the method comprises the steps that a ground fault processing device judges that a permanent low-resistance ground fault occurs in the power distribution network, when a ground fault line is selected, the fault line is not cut off, the device is not reset, during the duration of the ground fault, the displacement voltage of a neutral point of the power distribution network is unchanged, and the stable increment delta i of zero-sequence current in a feeder line is detected again0When the current is more than or equal to xi, the situation that the single-phase earth fault occurs again in the power distribution network in the period is judged, the subsequent fault is the same-name-phase low-resistance earth fault or the different-name-phase high-resistance earth fault, and the line of the subsequent fault is the line with the stable increment of the zero-sequence current;
after the earth fault processing device judges that the power distribution network has permanent high-resistance earth fault, the single-phase earth fault characteristics of the power distribution network still conform to delta U after the earth fault line is cut offN≥δ、Δi0When the voltage is more than or equal to xi, the single-phase earth fault still exists in the power distribution network, the fault needs to be processed continuously, the processing is carried out according to different processing methods of the earth fault processing device until the fault is recovered, and the device is reset after the earth fault is recovered;
the earth fault processing device judges that the power distribution network has a permanent low-resistance earth fault, and after an earth fault circuit is cut off, the neutral point displacement voltage stability increment of the power distribution network conforms to the following conditions: delta UNIs not less than delta, and the increment delta i of the zero sequence current of any line0And when the zero sequence current is larger than or equal to xi, indicating that a fault line still grounded in the power distribution network is still present, continuously processing and cutting off the line with the maximum zero sequence current until the zero sequence current reaches delta UN<Delta, increment of zero sequence current in each feeder line, delta i0<ξ；
Delta is an absolute increment value of the neutral point displacement voltage when the power grid has a ground fault, and the absolute value of delta is set according to the requirement of high-resistance grounding starting sensitivity and is larger than the change of the neutral point displacement voltage of the power grid caused by the voltage fluctuation of the power grid; xi is an increment standard value of the stable zero sequence current in the line when the earth fault occurs in the power distribution network, the value is set according to the detection sensitivity of high-resistance earth, the homonymy earth fault is a single-phase earth fault of different lines but the same phase, and the heteronymy earth fault is a single-phase earth fault of different lines and different phases.
2. The intelligent judgment and processing method for multiple earth faults of the power distribution network according to claim 1, characterized in that: the single-phase high-resistance earth fault and the single-phase low-resistance earth fault are divided by neutral point displacement voltage when U is usedN<UGLWhen it is a single-phase high-resistance earth fault, when it is UN≥UGLTime, single-phase low-resistance earth fault, UGLThe boundary value of the high-resistance earth fault and the low-resistance earth fault is 50% of the phase voltage.
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