CN113690865B - Quick handling method for single-phase disconnection fault of 10kV line - Google Patents

Quick handling method for single-phase disconnection fault of 10kV line Download PDF

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CN113690865B
CN113690865B CN202111244358.5A CN202111244358A CN113690865B CN 113690865 B CN113690865 B CN 113690865B CN 202111244358 A CN202111244358 A CN 202111244358A CN 113690865 B CN113690865 B CN 113690865B
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fault
phase
switch
voltage
line
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CN113690865A (en
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潘建兵
邓志祥
罗松林
郝钰
刘洋
徐在德
徐经民
郭亮
曹蓓
安义
邓才波
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Fuzhou Power Supply Branch Of State Grid Jiangxi Electric Power Co ltd
Nanchang Kechen Electric Power Test And Research Co ltd
State Grid Corp of China SGCC
Electric Power Research Institute of State Grid Jiangxi Electric Power Co Ltd
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Fuzhou Power Supply Branch Of State Grid Jiangxi Electric Power Co ltd
Nanchang Kechen Electric Power Test And Research Co ltd
State Grid Corp of China SGCC
Electric Power Research Institute of State Grid Jiangxi Electric Power Co Ltd
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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
    • G01R31/085—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution lines, e.g. overhead
    • 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
    • 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
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/54—Testing for continuity
    • 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
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/58—Testing of lines, cables or conductors
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/02—Details
    • H02H3/06—Details with automatic reconnection
    • H02H3/066—Reconnection being a consequence of eliminating the fault which caused disconnection
    • 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
    • H02H7/261—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 involving signal transmission between at least two stations
    • H02H7/263—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 involving signal transmission between at least two stations involving transmissions of measured values

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Mathematical Physics (AREA)
  • Theoretical Computer Science (AREA)
  • Emergency Protection Circuit Devices (AREA)

Abstract

The invention belongs to the technical field of distribution lines, and discloses a method for quickly handling a single-phase disconnection fault of a 10kV line.

Description

Quick handling method for single-phase disconnection fault of 10kV line
Technical Field
The invention relates to the technical field of distribution lines, in particular to a method for quickly handling single-phase line break faults of a 10kV line.
Background
The 10kV distribution line is affected by external natural factors, equipment aging, external force damage and other factors, disconnection faults often occur, the disconnection faults can cause the three-phase voltage and current on the load side to be asymmetric, and the generated negative sequence and zero sequence components can cause serious damage to various loads (particularly rotating equipment). In addition, the disconnection fault can also form a complex fault along with the grounding phenomenon, and if the disconnection fault is not timely taken, the complex fault can be developed into a cascading fault, so that personal injuries and deaths, fire, large-area power failure and equipment damage are caused.
At present, the detection and the positioning of the short-circuit fault of the distribution line are deeply researched at home and abroad, but the attention to the broken line fault is less. The traditional power system relay protection judges a ground fault and an interphase short-circuit fault by taking overcurrent as a characteristic, while the ground current and the short-circuit current of a disconnection fault are very weak, particularly occur at the tail end of a line, and the traditional power system relay protection cannot deal with the disconnection fault.
Therefore, a rapid processing method for single-phase disconnection fault identification, positioning, isolation and non-fault area recovery of a 10kV line is urgently needed, the shortage of the disconnection fault processing level is made up, and the disconnection fault is promoted to be applied in practical engineering.
Disclosure of Invention
The invention aims to provide a method for quickly handling a single-phase disconnection fault of a 10kV line, which is used for carrying out minute-level processing on the 10kV disconnection grounding fault by extracting the characteristics of voltage, current, phase and the like monitored by a switch and fusing the related technologies of voltage time type feeder automation and level difference relay protection, so that the quick identification, positioning and isolation of the disconnection fault and the recovery of power supply in a non-fault area are realized, the problems of mountain fire, personal electric shock, equipment damage and the like caused by the long-time existence of the disconnection fault are avoided, and the safety and reliability of power supply are improved.
The invention is realized by the following technical scheme, and discloses a method for quickly handling a single-phase disconnection fault of a 10kV line, which comprises the following steps:
step one, analyzing and identifying fault abnormality: the method comprises the steps that voltage, current and protection action data collected by a switch are collected and stored in real time, whether zero sequence voltage, zero sequence current, phase voltage, phase current and line current at the switch in adjacent collection periods are abnormal or not is compared, if the amplitude of the phase current is reduced by 20% or the change rate of three-phase load unbalance exceeds 30%, the voltage value of the low-voltage side of a nearest station area at the downstream of the switch and the voltage value change of the switch are collected, and at the moment, if at least one phase of the three-phase voltage value is reduced by 50%, the 10kV line is judged to have a line break fault;
step two, single-phase disconnection fault positioning: when the collected phase current amplitude of the 10KV line is reduced by 20% or the change rate of the three-phase load unbalance degree exceeds 30%, the position of a fault point can be judged by comparing the change conditions of the collected line voltage values of the switch. If the collected line voltage is not changed, and at least one line voltage of the other two line voltages is reduced by 50%, the line breaking position is positioned before the switch, otherwise, the line breaking position is positioned after the switch. The position of the broken line fault point can be judged through the phase current, when the amplitude of one phase current collected at the switch is reduced to 0, and the phase difference of the other two phases of current is more than 1500Then, we can judge that the disconnection position is in front of the switchOtherwise, the disconnection position is positioned behind the switch;
step three, single-phase disconnection fault isolation: the single-phase line break fault isolation is carried out according to the principle of time level difference and no-voltage brake-off treatment, namely, a first subsection or branch switch close to the upstream of the fault protects brake-off according to the line break fault, other fault upstream switches keep a switch-on state and are used as backup protection switches of the upstream of the fault, and the fault is prevented from existing for a long time; the first switch at the downstream of the fault is switched off and closed according to the loss of voltage, the section or branch switch at the downstream of the non-fault is switched off according to the loss of voltage, and the branch switch in the fault section is switched on according to the loss of voltage. Firstly, judging whether the duration time of the disconnection fault is greater than a set value, if so, carrying out tripping and closing operation of a switch in a disconnection fault interval, and simultaneously uploading disconnection fault information to a switch in a disconnecting state; starting a disconnection fault processing algorithm after a disconnection fault occurs, starting a closing or closing operation by the tie switch according to the duration time of the disconnection fault, and when the duration time of the disconnection fault is more than t1+ delta t, executing the closing operation by the tie switch, or executing the closing operation; when the fault position is a communication switch, whether the disconnection fault state duration is between the disconnection fault handling time t1 and t1+ delta t of the adjacent section switch or not is judged; if yes, the interconnection switch executes closing and locking operation; if not, the contact switch executes the closing operation;
step four, recovering power supply in the non-fault area: when the duration time of the disconnection fault is longer than t1+ delta t, the interconnection switch can execute a closing operation, and the reverse unoccluded switch receives a closing instruction to perform the closing operation to recover the power supply of the corresponding non-fault area.
Further preferably, in the step one, the specific process of identifying the single-phase disconnection fault is as follows: the abnormal criterion is that whether the phase current, the phase voltage and the line voltage in the adjacent sampling period of the switch exceed the limit value is compared, and the calculation formula of the limit value is as follows:
Figure 853194DEST_PATH_IMAGE001
Figure 238038DEST_PATH_IMAGE002
wherein T2 represents the current acquisition time, T1 represents the previous acquisition time, and T2-T1 are generally less than 0.25 ms;
Figure 506340DEST_PATH_IMAGE003
represents the a-phase current value at the present acquisition time,
Figure 734059DEST_PATH_IMAGE004
represents the a-phase current value at the previous acquisition time,
Figure 378798DEST_PATH_IMAGE005
represents the B-phase current value at the current acquisition time,
Figure 883729DEST_PATH_IMAGE006
represents the B-phase current value at the previous acquisition time,
Figure 572199DEST_PATH_IMAGE007
represents the C-phase current value at the current acquisition time,
Figure 769438DEST_PATH_IMAGE008
representing the C-phase current value at the previous acquisition moment;
when the acquired phase current or the three-phase load unbalance change rate meets any one of a formula (1) and a formula (2), starting and collecting the voltage value of the low-voltage side phase of the nearest station area at the downstream of the switch and the voltage value change of the switch line;
if the voltage value change of the low-voltage side phase of the transformer area meets the formula (3) or the voltage value change of the line at the switch meets the formula (4), judging that the 10kV line has a line break fault;
Figure 467135DEST_PATH_IMAGE009
Figure 436359DEST_PATH_IMAGE010
in the formula (I), the compound is shown in the specification,
Figure 436676DEST_PATH_IMAGE011
representing the a-phase voltage value at the current acquisition time,
Figure 373408DEST_PATH_IMAGE012
representing the a-phase voltage value at the previous acquisition instant,
Figure 359950DEST_PATH_IMAGE013
representing the B-phase voltage value at the current acquisition time,
Figure 698528DEST_PATH_IMAGE014
representing the B-phase voltage value at the previous acquisition moment;
Figure 745112DEST_PATH_IMAGE015
represents the C-phase voltage value at the current acquisition time,
Figure 44506DEST_PATH_IMAGE016
representing the C-phase voltage value at the previous acquisition instant,
Figure 84007DEST_PATH_IMAGE017
representing the line voltage between the AB two phases at the current acquisition time,
Figure 19034DEST_PATH_IMAGE018
representing the line voltage between the two phases at the previous acquisition instant AB,
Figure 485787DEST_PATH_IMAGE019
representing the line voltage between the two phases BC at the current acquisition time,
Figure 272478DEST_PATH_IMAGE020
representing the line voltage between the two phases BC at the previous acquisition instant,
Figure 600822DEST_PATH_IMAGE021
to representThe line voltage between the AC two phases at the current acquisition time,
Figure 913992DEST_PATH_IMAGE022
representing the line voltage between the two phases AC at the previous acquisition instant.
Preferably, the single-phase disconnection fault location is to distinguish the fault upstream and downstream, namely the forward and reverse parts, by comparing the phase current change value, the phase voltage and the line voltage change range; the forward decision condition should satisfy formula (5), the reverse decision condition should satisfy formula (6),
Figure 36800DEST_PATH_IMAGE023
Figure 576365DEST_PATH_IMAGE024
in the formula (I), the compound is shown in the specification,
Figure 692089DEST_PATH_IMAGE025
indicates the phase of the a-phase current at the current acquisition time,
Figure 610497DEST_PATH_IMAGE026
indicates the phase of the B-phase current at the current acquisition time,
Figure 104539DEST_PATH_IMAGE027
the phase of the C-phase current at the current acquisition time is shown.
Further preferably, the third specific process comprises the following steps: line break fault duration for sectionalizing switch
Figure 724876DEST_PATH_IMAGE028
Setting the level difference according to the value of the current value of the photo, including the line break fault duration of the feeder line outgoing switch and the section switch of the transformer substation
Figure 785236DEST_PATH_IMAGE028
The specific value is set according to the formula (7):
Figure 558151DEST_PATH_IMAGE029
where N represents the number of segments, t1 is the protection action value,
Figure 272030DEST_PATH_IMAGE030
is the adjacent switching time difference;
the fault upstream switch acts according to the duration of the disconnection fault and is greater than the set value
Figure 395974DEST_PATH_IMAGE028
Performing opening operation and closing operation, less than the set value
Figure 260025DEST_PATH_IMAGE028
The section switch of (1) does not act;
the fault downstream section switch acts according to the duration of the open fault, and the execution logic operates according to the formula (8).
Figure 483852DEST_PATH_IMAGE031
The tie switch operates according to the duration of the disconnection fault and the execution logic operates according to equation (9).
Figure 775156DEST_PATH_IMAGE032
The fault branch switch acts according to the duration of the disconnection fault, and the opening is executed according to the principle of voltage loss opening; secondly, performing delayed switching on according to power-on, and performing switching-on operation when the power-on is not obtained and locking; the time of power failure is longer than the time required by closing all section switches at the downstream of the fault.
Further preferably, the step four comprises the following specific processes: the switch in the non-fault area is switched on according to the power-on delay switching-on logic, and when the interconnection switch meets the condition that N1 in the formula (9) is more than 1, the interconnection switch executes the switching-on operation; the rest section switches and the branch switches can be automatically switched on and switched off in an incoming delay mode according to the traditional voltage time type feeder.
The invention has the advantages that: the method integrates the level difference protection and the voltage time type Feeder Automation (FA) technology to rapidly dispose the single-phase disconnection fault of the 10kV line, a switch manufacturer can configure a relevant parameter interface according to the method, and operation and maintenance personnel reasonably set a protection fixed value and FA parameters according to the actual situation of a field, so that the disconnection fault recognition, positioning and isolation of the 10kV line and the recovery of power supply in a non-fault area can be realized, the power failure range is reduced, and the secondary accident of the disconnection fault is avoided. By using the method, the level of rapid handling of the disconnection fault can be improved, the power supply recovery in the non-fault area at the level of minutes can be realized, the risk of accidents such as personal electric shock casualties, mountain fire and the like can be reduced, and the power supply safety and the high-quality service level can be improved.
Drawings
Fig. 1 is a schematic structural diagram of a 10kV line single-phase disconnection fault rapid processing control part.
Fig. 2 is a schematic diagram of a single-phase disconnection fault handling process of a distribution line.
Detailed Description
For ease of understanding, the present invention is illustrated in further detail below with reference to examples.
A10 kV line single-phase disconnection fault rapid processing method comprises four steps of fault abnormity analysis and identification, single-phase disconnection fault positioning, single-phase disconnection fault isolation and non-fault area power restoration, a 10kV line single-phase disconnection fault rapid processing control part is structurally shown in figure 1 and comprises an aviation plug type signal input port, an input signal processing unit, a power supply processing unit, a front-mounted microprocessor (STM 32, 9 × 12Bit for ADC, voltage, current and battery voltage processing), a microprocessor (STM 32F103ZE for disconnection, overcurrent, overload and grounding judgment and processing), a device power supply and control input interface, a GPRS/Beidou communication module, an RS232 interface and a network interface, wherein the device power supply and the control input interface are connected with the power supply processing unit and the microprocessor, the microprocessor is in signal connection with the GPRS/Beidou communication module, the RS232 interface and the network interface, and the input signal processing unit receives current, voltage and voltage acquired by the aviation plug type signal input port, Voltage, switching action information; the input signal processing unit inputs the processed electrical quantity information into the microprocessor, and the input signal processing unit inputs the processed opening and closing information into the front-end microprocessor.
Step one, analyzing and identifying fault abnormality: the fault abnormity analysis and identification can be used for identifying short-circuit faults, ground faults, overload faults and disconnection faults, and because the traditional three faults of short-circuit faults, ground faults and overload are more related to relay protection in the traditional power system and the technology is mature, the patent of the invention is not repeated, and only the single-phase disconnection faults are explained in detail.
The single-phase line break fault identification is to compare whether zero sequence voltage, zero sequence current, phase voltage, phase current and line current at the switch in adjacent acquisition periods are abnormal or not by acquiring and storing data such as voltage, current, protection action and the like collected at the switch in real time, if the amplitude of the phase current is reduced by 20% or the change rate of three-phase load unbalance exceeds 30%, collecting the voltage value of the low-voltage side phase of the nearest station area at the downstream of the switch and the voltage value change of the switch line, and if at least one phase of the three-phase voltage value is reduced by 50%, judging that a line break fault occurs in a 10kV line.
The abnormal criterion is that whether the phase current, the phase voltage and the line voltage in the adjacent sampling period of the switch exceed the limit value is compared, and the calculation formula of the limit value is as follows:
Figure 370085DEST_PATH_IMAGE033
Figure 647614DEST_PATH_IMAGE002
wherein T2 represents the current acquisition time, T1 represents the previous acquisition time, and T2-T1 are generally less than 0.25 ms;
Figure 378810DEST_PATH_IMAGE034
represents the a-phase current value at the present acquisition time,
Figure 450802DEST_PATH_IMAGE035
represents the a-phase current value at the previous acquisition time,
Figure 673973DEST_PATH_IMAGE036
represents the B-phase current value at the current acquisition time,
Figure 473302DEST_PATH_IMAGE037
represents the B-phase current value at the previous acquisition time,
Figure 75315DEST_PATH_IMAGE038
represents the C-phase current value at the current acquisition time,
Figure 833056DEST_PATH_IMAGE039
the C-phase current value at the previous acquisition time is indicated.
And when the acquired phase current or the three-phase load unbalance change rate meets any one of the formula (1) and the formula (2), starting to collect the voltage value of the low-voltage side phase of the nearest station area at the downstream of the switch and the voltage value change of the switch line.
And (3) judging that the 10kV line has a disconnection fault if the voltage value of the low-voltage side phase of the transformer area changes to satisfy a formula (3) or the voltage value of the line at the switch changes to satisfy a formula (4).
Figure 12364DEST_PATH_IMAGE040
Figure 628766DEST_PATH_IMAGE041
In the formula (I), the compound is shown in the specification,
Figure 600133DEST_PATH_IMAGE042
representing the a-phase voltage value at the current acquisition time,
Figure 13928DEST_PATH_IMAGE043
representing the a-phase voltage value at the previous acquisition instant,
Figure 946112DEST_PATH_IMAGE044
representing the B-phase voltage value at the current acquisition time,
Figure 352823DEST_PATH_IMAGE045
representing the B-phase voltage value at the previous acquisition moment;
Figure 929429DEST_PATH_IMAGE046
represents the C-phase voltage value at the current acquisition time,
Figure 763392DEST_PATH_IMAGE047
representing the C-phase voltage value at the previous acquisition instant,
Figure 792659DEST_PATH_IMAGE048
representing the line voltage between the AB two phases at the current acquisition time,
Figure 878427DEST_PATH_IMAGE049
representing the line voltage between the two phases at the previous acquisition instant AB,
Figure 558807DEST_PATH_IMAGE050
representing the line voltage between the two phases BC at the current acquisition time,
Figure 594632DEST_PATH_IMAGE051
representing the line voltage between the two phases BC at the previous acquisition instant,
Figure 94884DEST_PATH_IMAGE052
representing the line voltage between the AC two phases at the current acquisition time,
Figure 594129DEST_PATH_IMAGE053
representing the line voltage between the two phases AC at the previous acquisition instant.
Step two, single-phase disconnection fault positioning: when the phase current amplitude of the 10KV line is reduced by 20% or the change rate of the three-phase load unbalance degree exceeds 30%, the position of a fault point can be judged by comparing the change conditions of the line voltage values acquired by the switchAnd (4) placing. If the collected line voltage is not changed, and at least one line voltage of the other two line voltages is reduced by 50%, the line breaking position is positioned before the switch, otherwise, the line breaking position is positioned after the switch. The position of the broken line fault point can be judged through the phase current, when the amplitude of one phase current collected at the switch is reduced to 0, and the phase difference of the other two phases of current is more than 1500When the switch is opened, the disconnection position can be judged to be located in front of the switch, otherwise, the disconnection position is located behind the switch.
The single-phase line break fault location is to distinguish the fault upstream and downstream, i.e. the forward and reverse, by comparing the phase current change value, the phase voltage and the line voltage change range. The forward decision condition should satisfy formula (5), and the reverse decision condition should satisfy formula (6).
Figure 269961DEST_PATH_IMAGE023
Figure 445728DEST_PATH_IMAGE024
In the formula (I), the compound is shown in the specification,
Figure 449587DEST_PATH_IMAGE054
indicates the phase of the a-phase current at the current acquisition time,
Figure 1791DEST_PATH_IMAGE055
indicates the phase of the B-phase current at the current acquisition time,
Figure 532129DEST_PATH_IMAGE056
the phase of the C-phase current at the current acquisition time is shown.
Step three, single-phase disconnection fault isolation: the single-phase line break fault isolation is carried out according to the principle of time level difference and no-voltage brake-off treatment, namely, a first subsection or branch switch close to the upstream of the fault protects brake-off according to the line break fault, other fault upstream switches keep a switch-on state and are used as backup protection switches of the upstream of the fault, and the fault is prevented from existing for a long time; the first switch at the downstream of the fault is switched off and closed according to the loss of voltage, the section or branch switch at the downstream of the non-fault is switched off according to the loss of voltage, and the branch switch in the fault section is switched on according to the loss of voltage. Firstly, judging whether the duration time of the disconnection fault is greater than a set value, if so, carrying out tripping and closing operation of a switch in a disconnection fault interval, and simultaneously uploading disconnection fault information to a switch in a disconnecting state; starting a disconnection fault processing algorithm after a disconnection fault occurs, starting a closing or closing operation by the tie switch according to the duration time of the disconnection fault, and when the duration time of the disconnection fault is more than t1+ delta t, executing the closing operation by the tie switch, or executing the closing operation; when the fault position is a communication switch, whether the disconnection fault state duration is between the disconnection fault handling time t1 and t1+ delta t of the adjacent section switch or not is judged; if yes, the interconnection switch executes closing and locking operation; if not, the communication switch executes closing operation.
Line break fault duration for sectionalizing switch
Figure 895109DEST_PATH_IMAGE057
Setting the level difference according to the value of the current value of the photo, including the line break fault duration of the feeder line outgoing switch and the section switch of the transformer substation
Figure 635532DEST_PATH_IMAGE057
The specific value is set according to the formula (7):
Figure 208071DEST_PATH_IMAGE058
wherein, N represents the number of segments, e.g. there are 3 segment switches, N = 4; t1 is the protection action value, typically 0.05s,
Figure 717550DEST_PATH_IMAGE059
the adjacent switching time difference is generally 0.1-0.2 s.
The fault upstream switch acts according to the duration of the disconnection fault and is greater than the set value
Figure 376064DEST_PATH_IMAGE057
Performing opening operation and closing operation, less than the set value
Figure 354516DEST_PATH_IMAGE057
The section switch of (1) does not act.
The fault downstream section switch acts according to the duration of the open fault, and the execution logic operates according to the formula (8).
Figure 248522DEST_PATH_IMAGE060
The tie switch operates according to the duration of the disconnection fault and the execution logic operates according to equation (9).
Figure 363240DEST_PATH_IMAGE061
The fault branch switch acts according to the duration of the disconnection fault, and the opening is executed according to the principle of voltage loss opening; and secondly, performing delayed switching on according to the power-on, and performing switching on operation of the power-on locking. The time of power failure is longer than the time required by closing all section switches at the downstream of the fault.
Step four, recovering power supply in the non-fault area: and the non-fault area power supply recovery is an operation executed after fault isolation, when the duration time of the disconnection fault is longer than t1+ delta t, the contact switch executes a closing operation, and the reverse unoccluded switch receives a closing instruction to perform the closing operation to recover the power supply of the corresponding non-fault area. The switch in the non-fault area is switched on according to the power-on delay switching-on logic, and when the interconnection switch meets the condition that N1 in the formula (9) is more than 1, the interconnection switch executes the switching-on operation; other section switches and branch switches can automatically carry out power-on delay switching-on and power-off switching-off operations according to the traditional voltage time type feeder, the power-on delay time is generally set to be 7s, and the voltage-off switching-off limit value is 30V.
The specific case is shown in fig. 2. Normal power supply mode as shown in fig. 2 (a), the line is a typical single-connection mode, the section switches are D01, D02 and D03, the tie switch is L01, and the branch switch is F01. Suppose that when a disconnection fault occurs between D01 and D02.
Firstly, analyzing and identifying fault abnormality: according to the formula (3) and the formula (4), the CB1, the D01, the D02, the D03, the L01 and the F01 detect that the line is disconnected, as shown in fig. 2 (b).
Secondly, single-phase disconnection fault positioning: according to the formula (5) and the formula (6), CB1 and D01 are forward faults, namely upstream faults, and D02, D03, L01 and F01 are reverse faults, namely downstream faults. The fault is determined to be between D01-D02.
Thirdly, single-phase disconnection fault isolation: the characteristic duration of the disconnection fault is
Figure 192656DEST_PATH_IMAGE062
And the D01 switch executes a disconnection protection switching-off command and locks the switching-on operation. D02, D03, L01 and F01 meet the no-voltage switching-off logic due to the fact that disconnection faults are detected, namely D02, D03 and F01 are switched off, and D02 performs closing and locking operation according to the formula (8). As shown in (c) and (d) of FIG. 2.
Fourthly, recovering power supply in the non-fault area: according to the formula (9), the L01 switch satisfies the closing condition, and performs the closing operation, as shown in fig. 2 (e); according to the formula (8), and when the incoming call delay closing condition is satisfied, D03 performs a closing operation, as shown in fig. 2 (f); the branch switch F01 performs closing and locking operation due to long-time power failure, as shown in fig. 2 (i); and (3) uploading the action time sequence and message information of the CBs 1, the D01, the D02, the D03, the L01 and the F01, wherein the D01, the D02 and the F01 are all in an opening position and closing locking signal, judging that the fault is positioned between the D01 and the D02, and pushing the related fault section information to an operation and maintenance unit.
The single-phase disconnection fault handling method provided by the invention not only plays roles and selectivity of relay protection isolation faults, but also makes up for the functional deficiency that voltage time type disconnection faults cannot be processed, realizes quick positioning and isolation of disconnection faults and power restoration in non-fault areas, greatly avoids accidents such as personal electric shock, mountain fire, equipment damage and the like caused by non-isolation of disconnection faults, and improves power supply safety and reliability.

Claims (5)

1. A10 kV line single-phase disconnection fault handling method is characterized by comprising the following steps:
step one, analyzing and identifying fault abnormality: the method comprises the steps that voltage, current and protection action data collected by a switch are collected and stored in real time, whether zero sequence voltage, zero sequence current, phase voltage, phase current and line current at the switch in adjacent collection periods are abnormal or not is compared, if the amplitude of the phase current is reduced by 20% or the change rate of three-phase load unbalance exceeds 30%, the voltage value of the low-voltage side of a nearest station area at the downstream of the switch and the voltage value change of the switch are collected, and at the moment, if at least one phase of the three-phase voltage value is reduced by 50%, the 10kV line is judged to have a line break fault;
step two, single-phase disconnection fault positioning: when the phase current amplitude of the 10KV line is reduced by 20% or the change rate of the three-phase load unbalance degree exceeds 30%, the position of a fault point is judged by comparing the change conditions of the line voltage values acquired by the switch; if the collected line voltage is not changed, at least one line voltage of the other two line voltages is reduced by 50%, the line breaking position is determined to be positioned before the switch, otherwise, the line breaking position is positioned behind the switch; judging the position of the broken line fault point through the phase current, when the amplitude of the phase current collected at the switch is reduced to 0, and the phase difference of the other two phases of current is more than 1500If so, judging that the disconnection position is positioned in front of the switch, otherwise, judging that the disconnection position is positioned behind the switch;
step three, single-phase disconnection fault isolation: the single-phase line break fault isolation is carried out according to the principle of time level difference and no-voltage brake-off treatment, namely, a first subsection or branch switch close to the upstream of the fault protects brake-off according to the line break fault, other fault upstream switches keep a switch-on state and are used as backup protection switches of the upstream of the fault, and the fault is prevented from existing for a long time; the first switch at the downstream of the fault is switched off and closed according to the loss voltage, the section or branch switch at the downstream of the non-fault is switched off according to the loss voltage switching-off principle, and the branch switch in the fault sectionPerforming a voltage-loss locking and closing operation; firstly, judging whether the duration time of the disconnection fault is greater than a set value, if so, carrying out tripping and closing operation of a switch in a disconnection fault interval, and simultaneously uploading disconnection fault information to a switch in a disconnecting state; after the disconnection fault occurs, starting a disconnection fault processing algorithm, connecting a switch to start a closing or locking closing operation according to the disconnection fault duration, when the disconnection fault duration is more than t1+ delta t, and t1 is a protection action value,
Figure DEST_PATH_IMAGE001
connecting the switches to execute the closing operation for the time difference of the adjacent switches, otherwise executing the closing operation; when the fault position is a communication switch, whether the disconnection fault state duration is between the disconnection fault handling time t1 and t1+ delta t of the adjacent section switch or not is judged; if yes, the interconnection switch executes closing and locking operation; if not, the contact switch executes the closing operation;
step four, recovering power supply in the non-fault area: when the duration time of the disconnection fault is longer than t1+ delta t, the interconnection switch can execute a closing operation, and the reverse unoccluded switch receives a closing instruction to perform the closing operation to recover the power supply of the corresponding non-fault area.
2. The method for handling the single-phase disconnection fault of the 10kV line according to claim 1, wherein in the step one, the specific process of identifying the single-phase disconnection fault is as follows: the abnormal criterion is that whether the phase current, the phase voltage and the line voltage in the adjacent sampling period of the switch exceed the limit value is compared, and the calculation formula of the limit value is as follows:
Figure 568446DEST_PATH_IMAGE002
Figure DEST_PATH_IMAGE003
where T2 denotes the current acquisition time, T1 denotes the previous acquisition time, and T2-T1 are generally smallAt 0.25 ms;
Figure 829663DEST_PATH_IMAGE004
represents the a-phase current value at the present acquisition time,
Figure DEST_PATH_IMAGE005
represents the a-phase current value at the previous acquisition time,
Figure 826438DEST_PATH_IMAGE006
represents the B-phase current value at the current acquisition time,
Figure DEST_PATH_IMAGE007
represents the B-phase current value at the previous acquisition time,
Figure 147698DEST_PATH_IMAGE008
represents the C-phase current value at the current acquisition time,
Figure DEST_PATH_IMAGE009
representing the C-phase current value at the previous acquisition moment;
when the acquired phase current or the three-phase load unbalance change rate meets any one of a formula (1) and a formula (2), starting and collecting the voltage value of the low-voltage side phase of the nearest station area at the downstream of the switch and the voltage value change of the switch line;
if the voltage value change of the low-voltage side phase of the transformer area meets the formula (3) or the voltage value change of the line at the switch meets the formula (4), judging that the 10kV line has a line break fault;
Figure 967274DEST_PATH_IMAGE010
Figure DEST_PATH_IMAGE011
in the formula (I), the compound is shown in the specification,
Figure 32182DEST_PATH_IMAGE012
representing the a-phase voltage value at the current acquisition time,
Figure DEST_PATH_IMAGE013
representing the a-phase voltage value at the previous acquisition instant,
Figure 758829DEST_PATH_IMAGE014
representing the B-phase voltage value at the current acquisition time,
Figure DEST_PATH_IMAGE015
representing the B-phase voltage value at the previous acquisition moment;
Figure 516569DEST_PATH_IMAGE016
represents the C-phase voltage value at the current acquisition time,
Figure DEST_PATH_IMAGE017
representing the C-phase voltage value at the previous acquisition instant,
Figure 820512DEST_PATH_IMAGE018
representing the line voltage between the AB two phases at the current acquisition time,
Figure DEST_PATH_IMAGE019
representing the line voltage between the two phases at the previous acquisition instant AB,
Figure 423532DEST_PATH_IMAGE020
representing the line voltage between the two phases BC at the current acquisition time,
Figure DEST_PATH_IMAGE021
representing the line voltage between the two phases BC at the previous acquisition instant,
Figure 863740DEST_PATH_IMAGE022
representing the line voltage between the AC two phases at the current acquisition time,
Figure DEST_PATH_IMAGE023
representing the line voltage between the two phases AC at the previous acquisition instant.
3. The 10kV line single-phase disconnection fault handling method according to claim 2, wherein the second step is specifically as follows: the single-phase line break fault location is to distinguish the upstream and downstream of the fault, namely the forward and reverse parts, by comparing the phase current change value, the phase voltage and the line voltage change range; the forward judgment condition should satisfy the formula (5), and the reverse judgment condition should satisfy the formula (6);
Figure 526803DEST_PATH_IMAGE024
Figure DEST_PATH_IMAGE025
in the formula (I), the compound is shown in the specification,
Figure 318041DEST_PATH_IMAGE026
indicates the phase of the a-phase current at the current acquisition time,
Figure DEST_PATH_IMAGE027
indicates the phase of the B-phase current at the current acquisition time,
Figure 739400DEST_PATH_IMAGE028
the phase of the C-phase current at the current acquisition time is shown.
4. The 10kV line single-phase disconnection fault handling method according to claim 3, wherein the specific process of the third step is as follows: line break fault duration for sectionalizing switch
Figure DEST_PATH_IMAGE029
According to the current value of the pictureStep difference setting is carried out on the size of the step switch, and the duration time of the disconnection fault of the section switch
Figure 299694DEST_PATH_IMAGE029
The specific value is set according to the formula (7):
Figure 540183DEST_PATH_IMAGE030
where N represents the number of segments, t1 is the protection action value,
Figure 84297DEST_PATH_IMAGE001
is the adjacent switching time difference;
the fault upstream switch acts according to the duration of the disconnection fault and is greater than the set value
Figure 435644DEST_PATH_IMAGE029
Performing opening operation and closing operation, less than the set value
Figure 381603DEST_PATH_IMAGE029
The section switch of (1) does not act;
the fault downstream section switch acts according to the duration of the disconnection fault, and the execution logic operates according to a formula (8);
Figure DEST_PATH_IMAGE031
the interconnection switch acts according to the duration of the disconnection fault, and the execution logic operates according to a formula (9);
Figure 386468DEST_PATH_IMAGE032
the fault branch switch acts according to the duration of the disconnection fault, and the opening is executed according to the principle of voltage loss opening; secondly, performing delayed switching on according to power-on, and performing switching-on operation when the power-on is not obtained and locking; the time of power failure is longer than the time required by closing all section switches at the downstream of the fault.
5. The 10kV line single-phase disconnection fault handling method according to claim 4, wherein the step four specifically comprises the following processes: the switch in the non-fault area executes the closing operation according to the power-on delay closing logic, and when the interconnection switch meets the condition that N1 in the formula (9) is more than 1, the interconnection switch executes the closing operation; and the rest section switches and the branch switches are operated according to voltage time type feeder automation incoming delay switching-on and power-off switching-off.
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