CN116316487A - Fault self-healing method and system for distribution line - Google Patents
Fault self-healing method and system for distribution line Download PDFInfo
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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
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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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- 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
- G01R31/52—Testing for short-circuits, leakage current or ground faults
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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
- G01R31/50—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
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- 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
- H02H3/027—Details with automatic disconnection after a predetermined time
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- 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
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/001—Methods to deal with contingencies, e.g. abnormalities, faults or failures
- H02J3/00125—Transmission line or load transient problems, e.g. overvoltage, resonance or self-excitation of inductive loads
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/007—Arrangements for selectively connecting the load or loads to one or several among a plurality of power lines or power sources
- H02J3/0073—Arrangements for selectively connecting the load or loads to one or several among a plurality of power lines or power sources for providing alternative feeding paths between load and source when the main path fails, e.g. transformers, busbars
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- 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 belongs to the technical field of power distribution network fault processing, and particularly relates to a fault self-healing method and a system of a power distribution line, wherein the residual voltage time limit of a sectional switch is set to be shorter when the residual voltage time limit is shorter when the power distribution line is closer to a power supply point, when a certain section on the power distribution line has a ground fault, only an upstream switch closest to the fault point is disconnected, and the rest switches on the upstream of the fault point still keep in position; when the fault type is a permanent fault, only the downstream switch nearest to the fault point executes opening and closing and locking reverse closing, and the interconnecting switch executes closing to complete power transfer of a downstream section of the fault area.
Description
Technical Field
The invention belongs to the technical field of power distribution network fault handling, and particularly relates to a fault self-healing method and system for a power distribution line.
Background
Feeder automation (Feeder Automation, FA for short), i.e. distribution line automation, is to monitor the operation of distribution lines by using an automation device, discover line faults in time, quickly locate and isolate fault areas, and quickly restore power to non-fault areas. The feeder automation is divided into centralized type and local type, wherein the centralized type refers to judging a fault area by means of the cooperation of a terminal and a main station by means of communication means, isolating faults by remote control of the main station and recovering power supply of a non-fault area; the in-situ mode means that the master station is not dependent on mutual communication of protection coordination, time sequence coordination or terminals, fault isolation is achieved, and power restoration in a non-fault area is achieved. In the existing on-site superposition type FA (feeder automation) fault processing, firstly, a line switch is not selectively tripped, then fault positioning and isolation are realized in a step-by-step superposition mode, a fixed timing power restoration is set for a downstream non-fault section by adopting statistics of the number of full-line sectional switches, the fault processing time is long, and the influence on the upstream and downstream loads of a fault point non-fault area is large.
Disclosure of Invention
The invention aims to provide a fault self-healing method and system for a distribution line, which are used for solving the problem that the time from power failure to re-power failure of a non-fault section is long due to long fault processing time when the existing local superposition type FA fault processing is carried out.
In order to solve the technical problems, the invention provides a fault self-healing method of a distribution line, which comprises the following steps:
1) Setting residual voltage time limit of sectional switch on distribution line: the closer to the power supply point, the shorter the residual voltage time limit;
2) When a certain section on the distribution line has a ground fault, a switch closest to the fault point in the switch upstream of the fault point trips to cut off the fault; the fault point upstream switch comprises a sectionalizing switch or an outgoing switch;
3) When the switch closest to the fault point in the upstream switch of the fault point trips, the downstream sectionalized switch loses voltage but keeps the closing position, and the instantaneous residual voltage detection is started; the switch closest to the fault point in the switch at the upstream of the fault point is subjected to split-phase reclosing; the instantaneous residual pressure detection is used for detecting the duration time of the instantaneous residual pressure;
when the fault is transient fault, the switch closest to the fault point in the upstream switch of the fault point is successfully reclosed, and the downstream switch recognizes that the transient residual voltage switching-off logic is not satisfied, so that the downstream switch still keeps on; if the duration of the instantaneous residual voltage reaches the residual voltage time limit, the instantaneous residual voltage brake-separating logic is satisfied, and if the duration of the instantaneous residual voltage is smaller than the residual voltage time limit, the instantaneous residual voltage brake-separating logic is not satisfied;
when the fault type is a permanent fault, the upstream switch delays to trip the coincident phase, the downstream switch detects instantaneous residual voltage at the moment, and the downstream switch nearest to the fault point executes opening and locking reverse closing; and the contact switch performs switching-on to finish power transfer of the downstream section of the fault area.
The beneficial effects are as follows: by the method, when the distribution line breaks down, only the upstream switch closest to the fault point is rapidly disconnected, the rest switches are not disconnected, so that a non-fault section upstream of the fault point still keeps normal power supply, and when the upstream switch closest to the fault point is disconnected, the downstream switch of the fault point is in voltage loss, but based on the method, the downstream switch closest to the fault point is in voltage loss but not disconnected, instantaneous residual voltage detection is started, when the fault type is transient fault, the rest switches can be switched on successfully because the upstream switch closest to the fault point is not met, the downstream switches are not disconnected because of the residual voltage time limit, the rest switches still keep on, and when the fault type is permanent fault, the upstream switch closest to the fault point is delayed to open a coincident phase, and based on the setting that the residual voltage time limit is shorter, only the downstream switch closest to the fault point is used for executing fault-free memory residual voltage disconnection and locking reverse switching on, therefore, when the distribution line is in permanent fault, the rest switches are disconnected, the fault state is not normally influenced because the upstream switch closest to the fault point is disconnected, the rest switches are not switched on, and the rest switches are not normally switched on when the fault section is disconnected.
Further, in the step 2), the current self-adaptive quick-break protection is adopted to realize tripping and fault removal of a switch closest to a fault point in the switch at the upstream of the fault point; the current self-adaptive quick-break protection comprises setting of over-current protection setting of an outgoing line switch and over-current protection setting of a sectionalizing switch, which are sequentially reduced.
Through setting up the outgoing line switch overcurrent protection setting, the sectionalizing switch overcurrent protection setting and the demarcation switch overcurrent protection setting that reduce in proper order, can make when the circuit trouble, sectionalizing switch break before the outgoing line switch, and then when the trouble, the sectionalizing switch of other upper reaches still can continue the power supply based on the outgoing line switch, adopts the current self-adaptation to trip down the regional power failure scope of fault point upper reaches on the spot promptly.
Further, the current adaptive quick-break protection further includes: the self-adaptive setting is adopted to reconfigure the current quick-break protection of the sectionalizing switch so as to avoid the override trip of the sectionalizing switch.
According to the invention, the current quick-break protection is configured on the segmented switches, namely, the segmented switches at different positions are configured with the current quick-break protection according to the positions, so that when a fault occurs, only the upstream switch closest to the fault point is disconnected, the process that the upstream non-fault area is affected by the fault and cannot normally supply power is avoided, and the power failure range of the upstream non-fault area is reduced.
Further, in step 1), three-stage current protection is also configured for the outlet switch.
For the outgoing line switch, three-section current protection can be configured, because the time limit of overcurrent protection is 0.3s when three-stage level difference is adopted, and a time level difference is reserved for the current protection when the three-stage level difference is configured, so that the outgoing line switch can be ensured to be cut off rapidly (faster than overcurrent protection cutting off) when faults occur between the outgoing line switch and the first section switch.
In step 3), the instantaneous residual voltage detection is started by losing voltage at one side, the acceleration transfer time is determined according to the residual voltage duration, and the contact switch is controlled to execute switching-on according to the acceleration transfer time.
The XL time of the traditional tie switch (namely XL time limit, the XL time limit of the traditional tie switch is the time of the single-side voltage-losing time-delay closing process of the traditional tie switch) is started to time by one-side voltage-losing, the closing and supplying are carried out after the time meets a set value, the set value is fixed, the set value is relatively long for ensuring the reliability of the transferring, the time which can be adaptively adjusted is adopted, and the time is obtained based on different fault points, so that the transferring and supplying process can be realized as quickly and reliably as possible. The method based on residual voltage time limit differential matching reduces the power restoration time of the downstream non-fault section, and further when a certain section on the distribution line breaks down, the rest non-fault sections can be quickly restored.
In order to solve the technical problem, the invention also provides a fault self-healing system of the distribution line, which comprises a processor, wherein the processor is used for executing instructions to realize the following steps:
1) Setting residual voltage time limit of sectional switch on distribution line: the closer to the power supply point, the shorter the residual voltage time limit;
2) When a certain section on the distribution line has a ground fault, a switch closest to the fault point in the switch upstream of the fault point trips to cut off the fault; the fault point upstream switch comprises a sectionalizing switch or an outgoing switch;
3) When the switch closest to the fault point in the upstream switch of the fault point trips, the downstream sectionalized switch loses voltage but keeps the closing position, and the instantaneous residual voltage detection is started; the switch closest to the fault point in the switch at the upstream of the fault point is subjected to split-phase reclosing; the instantaneous residual pressure detection is used for detecting the duration time of the instantaneous residual pressure;
when the fault is transient fault, the switch closest to the fault point in the upstream switch of the fault point is successfully reclosed, and the downstream switch recognizes that the transient residual voltage switching-off logic is not satisfied, so that the downstream switch still keeps on; if the duration of the instantaneous residual voltage reaches the residual voltage time limit, the instantaneous residual voltage brake-separating logic is satisfied, and if the duration of the instantaneous residual voltage is smaller than the residual voltage time limit, the instantaneous residual voltage brake-separating logic is not satisfied;
when the fault type is a permanent fault, the upstream switch delays to trip the coincident phase, the downstream switch detects instantaneous residual voltage at the moment, and the downstream switch nearest to the fault point executes opening and locking reverse closing; and the contact switch performs switching-on to finish power transfer of the downstream section of the fault area.
The beneficial effects are as follows: by the system, when a distribution line breaks down, only the upstream switch closest to the fault point is rapidly disconnected, the rest switches are not disconnected, so that a non-fault section upstream of the fault point still keeps normal power supply, and when the upstream switch closest to the fault point is disconnected, the downstream switch of the fault point is in voltage loss, but based on the system, the downstream switch closest to the fault point is in voltage loss but not disconnected, instantaneous residual voltage detection is started, when the fault type is transient fault, the rest switches can be switched on successfully because the upstream switch closest to the fault point is not met, the downstream switches are not disconnected because of the residual voltage time limit, the rest switches still keep on, and when the fault type is permanent fault, the upstream switch closest to the fault point is delayed to be disconnected to coincide with each other, and based on the setting that the residual voltage time limit is shorter, only the downstream switch closest to the fault point is used for executing fault-free memory residual voltage disconnection and locking reverse switching on, therefore, when the distribution line is in permanent fault, the fault type is in voltage loss, the rest switches are disconnected, the fault state is not normally influenced, the rest switches are disconnected, and the power supply section is not normally switched on because the upstream switch is disconnected.
Further, in the step 2), the current self-adaptive quick-break protection is adopted to realize tripping and fault removal of a switch closest to a fault point in the switch at the upstream of the fault point; the current self-adaptive quick-break protection comprises setting of over-current protection setting of an outgoing line switch and over-current protection setting of a sectionalizing switch, which are sequentially reduced.
Through setting up the outgoing line switch overcurrent protection setting, the sectionalizing switch overcurrent protection setting and the demarcation switch overcurrent protection setting that reduce in proper order, can make when the circuit trouble, sectionalizing switch break before the outgoing line switch, and then when the trouble, the sectionalizing switch of other upper reaches still can continue the power supply based on the outgoing line switch, adopts the current self-adaptation to trip down the regional power failure scope of fault point upper reaches on the spot promptly.
Further, the current adaptive quick-break protection further includes: the self-adaptive setting is adopted to reconfigure the current quick-break protection of the sectionalizing switch so as to avoid the override trip of the sectionalizing switch.
According to the invention, the current quick-break protection is configured on the segmented switches, namely, the segmented switches at different positions are configured with the current quick-break protection according to the positions, so that when a fault occurs, only the upstream switch closest to the fault point is disconnected, the process that the upstream non-fault area is affected by the fault and cannot normally supply power is avoided, and the power failure range of the upstream non-fault area is reduced.
Further, in step 1), three-stage current protection is also configured for the outlet switch.
For the outgoing line switch, three-section current protection can be configured, because the time limit of overcurrent protection is 0.3s when three-stage level difference is adopted, and a time level difference is reserved for the current protection when the three-stage level difference is configured, so that the outgoing line switch can be ensured to be cut off rapidly (faster than overcurrent protection cutting off) when faults occur between the outgoing line switch and the first section switch.
In step 3), the instantaneous residual voltage detection is started by losing voltage at one side, the acceleration transfer time is determined according to the residual voltage duration, and the contact switch is controlled to execute switching-on according to the acceleration transfer time.
The XL time of the traditional tie switch (namely XL time limit, the XL time limit of the traditional tie switch is the time of the single-side voltage-losing time-delay closing process of the traditional tie switch) is started to time by one-side voltage-losing, the closing and supplying are carried out after the time meets a set value, the set value is fixed, the set value is relatively long for ensuring the reliability of the transferring, the time which can be adaptively adjusted is adopted, and the time is obtained based on different fault points, so that the transferring and supplying process can be realized as quickly and reliably as possible. The method based on residual voltage time limit differential matching reduces the power restoration time of the downstream non-fault section, and further when a certain section on the distribution line breaks down, the rest non-fault sections can be quickly restored.
Drawings
FIG. 1 is a minimum line length of the present inventionl min A change rule diagram of the ratio of the back side impedance of the terminal to the minimum impedance of the system;
FIG. 2 is a schematic diagram of the protection range of the adaptive current snap-off protection at different line lengths according to the present invention;
FIG. 3 is a time-set fit of the transient residual calendaring time-gating logic function of the present invention;
FIG. 4 is a schematic diagram of the present invention following a C-section fault protection trip;
FIG. 5 is a schematic diagram showing the coincidence of the switch selections after the present stage trip;
fig. 6 is a schematic diagram showing the coincidence of the switch selections after override trip of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent.
Fault self-healing system embodiment of distribution line:
in this embodiment, the switches used on the distribution line are all phase-splitting switches, i.e., the outlet switch, the sectionalizer, the demarcation switch and the interconnection switch on the distribution line are all phase-splitting switches. In order to reduce the power outage range of the non-fault area upstream of the fault point and reduce the power restoration time of the non-fault area downstream of the fault point when a fault occurs, namely, when a fault occurs in a certain section of the distribution line, the embodiment performs the following processes to ensure the power consumption of the non-fault area:
in order to reduce the power outage range of the non-fault area upstream of the fault point, the embodiment performs the following configuration process: to reduce the probability of override trip, the present embodiment contemplates an inter-phase fault protection configuration scheme employing time level difference coordination. Considering the capability of a transformer and the like to bear short-circuit current, the longest tripping time allowed by current protection in a transformer substation is 0.3s, but step-by-step matching cannot be realized for a multi-section line, so that the layered configuration is considered, specifically, the overcurrent protection of an outgoing line switch is set to be 0.3s, the overcurrent protection of all section switches is set to be 0.15s, and the overcurrent protection of all demarcation switches is set to be 0s.
For the outgoing line switch, three-section current protection can be configured, because the time limit of overcurrent protection is 0.3s when three-stage level difference is adopted, and a time level difference is reserved for the current protection when the three-stage level difference is configured, so that the outgoing line switch can be ensured to be cut off rapidly (faster than overcurrent protection cutting off) when faults occur between the outgoing line switch and the first section switch. The current quick-break protection is set according to the three-phase short circuit at the tail end of the current stage line in the maximum operation mode, and the current quick-break protection with the time limit is matched with the current quick-break protection of the next stage line, wherein the time limit is 0.15s; the overcurrent protection is set according to the maximum load current, and the time limit is 0.3s, so that the overcurrent protection is used as the far backup protection of the full-line protection and the near backup protection of the current level line.
When the over-current protection is configured according to the principle, the problem of the override trip of the first sectionalizer exists when all sections formed by the sectionalizers on the line are in fault, but because the over-current protection action time is 0.15s, the current quick-break protection can be reconfigured for all the sectionalizers so as to avoid the override trip as far as possible. In order to avoid the problem of complex setting caused by current quick-break protection, a self-adaptive setting method can be adopted.
The self-adaptive setting technology is to calculate the short-circuit current value of the protected section line end when the short circuit occurs on line according to the current running state and the fault type of the system, and then set the protection in real time according to the principle of avoiding the current value, and the calculation method of the on-line setting value is shown as the formula (1). Here, for simplicity of calculation, since the line impedance angle and the system impedance angle are assumed to be the same, equation (1) is in scalar form.
In the method, in the process of the invention,E S the equivalent potential of the system can be calculated in real time according to the measured voltage;Z L is the line impedance, typically 0.4. Delta./km;Z eq is the equivalent impedance of the back side of the terminal, and is actually the equivalent impedance of the systemZ S Impedance with upstream linel u Z L The sum of the two values,l u for the length of the upstream line,Z eq the voltage and current fault components can be calculated in real time;k rel in order for the coefficient of reliability to be a good factor,k k as a fault type coefficient, when two phases are short-circuited
When the three phases are in failure, the three-phase is 1,lthe line length of the protected section for the present stage.
Thus, the setting calculation of the fixed value can be simplified, and only the line length of the protected section is required to be presetlThe principle of branching demarcation is not changed in this scheme, so the line length is mainly based on the main line. When the grid frame is fixed and only power supply is considered, the lengths of the forward section and the reverse section can be preset and stored in the local power distribution terminal; when the net rack has large fluctuation, the section lines need to be recalculated according to the topology fluctuation conditionAnd the path length is issued to the terminal.
The protection scope of the self-adaptive quick-break protection is analyzed, and the protection scope of the self-adaptive quick-break protection is related to the length, the reliability coefficient and the equivalent impedance of the back side of the terminal of the protected section line, as shown in the formula (2).
It can also be seen from equation (2) that the adaptive current protection at a certain back-side equivalent impedance and reliability factor may also be out of protection due to the short protected line. The minimum line length with the protection range is as follows:
according to the condition that the short-circuit current level of the bus of the 10kV transformer substation cannot exceed 25kA, the minimum equivalent impedance of the system can be obtainedZ S.min Is 0.23 omega, and the ratio of the equivalent impedance of the back side of the terminal to the minimum equivalent impedance of the system is assumed to be
The change rule of the minimum line length with the minimum impedance ratio of the terminal backside impedance to the system minimum impedance in the self-adaptive quick-break protection range after the reliability coefficient is respectively 1.1 and 1.2 is shown in figure 1. When the ratio of the back-side impedance of the terminal to the minimum impedance of the system is 20, the change rule of the protection range of the self-adaptive current quick-break protection along with the length of the line is shown in fig. 2.
It can be seen from fig. 1 and fig. 2 that the protection range of the self-adaptive current quick-break protection is affected by the equivalent impedance of the back side of the terminal and the length of the protected line, when the protected line is too short, the quick-break protection will also occur without the protection range, the smaller the equivalent impedance of the back side of the terminal, the larger the minimum line length with the protection range, and the larger the reliability coefficient, the larger the minimum line length. When the equivalent impedance of the back side is fixed, the longer the circuit is, the larger the protection range is, and the smaller the reliability coefficient is, the larger the protection range is.
The comprehensive analysis shows that the self-adaptive current protection can overcome the problem of override trip to a certain extent, and meanwhile, the engineering practicability is improved due to the adoption of the self-adaptive setting technology. It should be noted here that, whether only two terminals of the line voltage transformers or three-phase voltage transformers are configured, the equivalent impedance of the back side of the terminal can be calculated by a symmetrical component method, so that it is also feasible to implement adaptive current protection under the existing engineering configuration.
Compared with the phase-to-phase fault transformer substation outlet switch tripping time, the configuration of single-phase ground fault protection is limited by 0.3s, and single-phase ground fault processing is not limited by the time, so that the minimum-range isolation of single-phase ground faults can be realized by adopting the thought of step-by-step level difference matching. The specific time of the demarcation switches PS 1-PS 4 can be set to be 2-5 s, so that the delay is long, because the single-phase grounding fault processing is not required to be fast, and the trip rate is too high to avoid the influence on the power supply reliability during transient faults; for the sectionalizing switch, consider time-limited coordination with the end demarcation switch PS4, with FB4, FB3, FB2, FB1, CB being 0.5s in sequence. Taking the operation time of PS 1-PS 4 as 5s as an example, the operation time of FB4, FB3, FB2, FB1 and CB is sequentially 5.5s, 6s, 6.5s, 7s and 7.5s.
In order to reduce the recovery time of the non-fault area downstream of the fault point, the following residual voltage switching-off strategy process based on time limit matching is performed in the embodiment: besides the phase-splitting switch with permanent fault recognition function and the protection configuration, the voltage-losing and switching-off element logic with fault memory is changed into the voltage-losing and switching-off element logic with fault memory for accelerating the power restoration time of the downstream of the fault point. In addition, all the sectionalizers without fault memory are put into residual voltage breaking logic with time limit. The non-fault memory residual voltage switching-off is that for a switch which does not sense fault current or meets single-phase earth fault detection criteria, when the switch senses voltage when the upper-level line phase splitting is coincident, the switch is switched off and closed in the reverse direction. To ensure a fault-free registration only close to the fault pointThe switch is separated by adopting a time limit matching mode, specifically, the action time limit is shorter as the switch is closer to a power supply point, the time difference can be 0.05s in consideration of the fact that the action time of the whole group of switches is generally less than 0.1s, and the residual voltage time limit is the time differenceT RP The setting is specifically shown in formula (4), and the specific configuration is shown in fig. 3.
In the middle ofNThe number of the sectionalizing switches.
In order to ensure the residual voltage time limit switching-off of the downstream sectionalizer at the fault point, the tripping time after the sectionalizers are overlapped is set to be 1.2 times of the residual voltage time limit of the farthest sectionalizer in consideration of reliability. The reset condition of the residual voltage time limit brake-separating logic is that the residual voltage time limit is not met or the three-phase incoming call is made.
Taking the phase-to-phase fault of the section B shown in fig. 3 as an example, the upstream switch CB and the FB1 at the fault point can both sense fault memorization, and the fault is supposed to be removed by the fast breaking protection trip of the FB 1; at the moment, the downstream switches FB 2-FB 4 at the fault points lose voltage but keep the same position, and instantaneous residual voltage detection is started; then, FB1 starts the split-phase reclosing when the switch is in the split position due to fault memorization, and starts to identify fault properties. And when the fault is an instantaneous fault, the FB1 is successfully overlapped, and the FB 2-FB 4 does not meet the condition that the instantaneous residual voltage logic is always kept in the closed position, so that the B-E sections recover power supply. When the fault is a permanent fault, the FB1 delays to trip the coincident phase, and the transient residual voltage can be detected by the FB 2-FB 4 in the period, but the action outlet time of the FB2 is shorter, so that the FB2 firstly executes fault-free memory residual voltage brake opening and locks reverse brake closing; FB3, FB4 does not reach the action exit time, keep closing the position and reset the instantaneous residual voltage and break the gate logic; and then the contact switch LS1 performs switching-on to finish C-E section power conversion.
According to the process, if the residual voltage delay switching-off strategy of level difference matching is adopted, the downstream switch of the fault point is not sequentially switched on, and the non-fault section power restoration process of the downstream of the fault point can be quickened.
Based on the configuration of the phase-splitting switch with permanent fault identification function, which is adopted by the outgoing switch, the sectionalizing switch, the demarcation switch and the interconnection switch on the distribution line in the embodiment, when an inter-phase fault and a single-phase earth fault occur on the distribution line, the following processing procedures can be realized:
1) And (3) an in-situ FA fault handling process during quick-break protection tripping.
(1) As shown in fig. 4, after the phase-to-phase short circuit fault occurs in the section c, when the current of the current stage FB2 reaches the setting value of the quick-break protection, the FB2 trips (t=0s); FB3 and FB4 lose voltage but do not break the gate, and immediately start the instantaneous residual voltage detection; meanwhile, the instantaneous residual voltage detection is started by the voltage loss at one side of the contact switch LS 1.
(2) As shown in fig. 5, the protection sectionalizer FB2 of this stage determines a BC interphase short-circuit fault according to the phase selection element, performs primary split-phase reclosing after 0.3s, overlaps the a phase first, overlaps the B phase after 0.05s (t=0.35 s), and then performs fault property discrimination.
(3) And when the transient fault is judged, the FB2 is quickly overlapped with the C phase, and the double-electricity is completed after the closing is successful. LS1 stops the transfer timing, and FB 3-FB 4 return to the residual voltage time limit logic.
(4) When the permanent fault is determined, the FB2 delays to trip the AB phase and close the forward switch, during which time the fault point downstream segments FB3, FB4, LS1 all detect the instantaneous residual voltage, and when t=0.55 s, FB3 simultaneously performs the switch-off and closes the reverse switch. The FB4 residual pressure duration is not met, the outlet is reset, and the opening brake is closed.
(5) The contact switch LS1 detects the duration time of the instantaneous residual voltage to be 0.2s, the contact time is self-set to be 0.24s, namely, the time is 0.24s after the LS1 detects the disappearance of the instantaneous residual voltage, and the switching-on is performed to finish the switching-on power supply.
2) And (3) an in-situ FA processing flow when overcurrent protection tripping.
As shown in fig. 6, the section C has short circuit fault, but the fault current does not reach the quick-break setting value, the FB2 is quick-break and not operated, and the FB1 and the FB2 delay overload protection trip.
(1) The sectionalizing switch FB1 determines BC interphase short-circuit fault according to the phase selecting element. FB1 performs split-phase reclosing after 0.3s, and according to the phase selection result, the phase a is overlapped first, the phase B is overlapped after 0.05s, then fault property discrimination is performed, it is determined that the front part has no fault, the phase C is overlapped rapidly, and the reclosing is successful.
(2) FB2 has fault memory and is in a brake-separating position, phase-separating permanent fault identification is carried out after 0.3s, and the following FA process is the same as the above.
3) Single-phase earth fault handling flow.
The protection tripping of the single-phase earth fault adopts time level difference matching, and takes the phase A earth fault of the section C as an example.
(1) The stage of the sectionalizer switch FB2 detects single-phase earth faults, and after the delay condition is met, the sectionalizer switch FB2 trips before FB 1; FB3 and FB4 lose voltage but do not break the gate, and immediately start the instantaneous residual voltage detection; meanwhile, the step-down on one side of the contact switch LS1 starts timing, and the instantaneous residual voltage detection is started.
(2) The protection sectionalizer FB2 determines the grounding fault of the phase A according to the phase selection element, performs primary split-phase reclosing after 0.3s (t=0.3 s), and firstly coincides with the phase B to judge the fault property.
(3) And when the transient fault is judged, the FB2 rapidly coincides with the AC phase, and the double-electricity is completed after the closing is successful. LS1 stops the transfer timing, and FB 3-FB 4 return to the residual voltage time limit logic.
(4) When the permanent fault is determined, the FB2 delays to trip the B-phase and locks the forward closing, during which time the fault point downstream segments FB3, FB4, LS1 all detect the instantaneous residual voltage, and when t=0.5 s, FB3 simultaneously performs the opening and locking the reverse closing. The FB4 residual pressure duration is not met, the outlet is reset, and the opening brake is closed.
(5) The contact switch LS1 detects the duration time of the instantaneous residual voltage to be 0.2s, the contact time is self-set to be 0.24s, namely, the time is 0.24s after the LS1 detects the disappearance of the instantaneous residual voltage, and the switching-on is performed to finish the switching-on power supply.
Fault self-healing method embodiment of distribution line:
the fault self-healing method of the distribution line can be realized through a fault self-healing system of the distribution line, and the process of the fault self-healing method of the distribution line is realized through the fault self-healing system of the distribution line, which is described in detail in the embodiment of the fault self-healing system of the distribution line and is not repeated here.
The above description is only a preferred embodiment of the present invention, and the patent protection scope of the present invention is defined by the claims, and all equivalent structural changes made by the specification and the drawings of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The fault self-healing method for the distribution line is characterized by comprising the following steps of:
1) Setting residual voltage time limit of sectional switch on distribution line: the closer to the power supply point, the shorter the residual voltage time limit;
2) When a certain section on the distribution line has a ground fault, a switch closest to the fault point in the switch upstream of the fault point trips to cut off the fault; the fault point upstream switch comprises a sectionalizing switch or an outgoing switch;
3) When the switch closest to the fault point in the upstream switch of the fault point trips, the downstream sectionalized switch loses voltage but keeps the closing position, and the instantaneous residual voltage detection is started; the switch closest to the fault point in the switch at the upstream of the fault point is subjected to split-phase reclosing; the instantaneous residual pressure detection is used for detecting the duration time of the instantaneous residual pressure;
when the fault is transient fault, the switch closest to the fault point in the upstream switch of the fault point is successfully reclosed, and the downstream switch recognizes that the transient residual voltage switching-off logic is not satisfied, so that the downstream switch still keeps on; if the duration of the instantaneous residual voltage reaches the residual voltage time limit, the instantaneous residual voltage brake-separating logic is satisfied, and if the duration of the instantaneous residual voltage is smaller than the residual voltage time limit, the instantaneous residual voltage brake-separating logic is not satisfied;
when the fault type is a permanent fault, the upstream switch delays to trip the coincident phase, the downstream switch detects instantaneous residual voltage at the moment, and the downstream switch nearest to the fault point executes opening and locking reverse closing; and the contact switch performs switching-on to finish power transfer of the downstream section of the fault area.
2. The fault self-healing method of a distribution line according to claim 1, wherein in step 2), the tripping and fault removal of a switch closest to a fault point in a switch upstream of the fault point is realized by adopting current self-adaptive quick-break protection; the current self-adaptive quick-break protection comprises setting of over-current protection setting of an outgoing line switch and over-current protection setting of a sectionalizing switch, which are sequentially reduced.
3. The method for fault self-healing of a distribution line according to claim 2, wherein the current adaptive quick-break protection further comprises: the self-adaptive setting is adopted to reconfigure the current quick-break protection of the sectionalizing switch so as to avoid the override trip of the sectionalizing switch.
4. A method of fault self-healing of an electrical distribution line according to claim 3, wherein in step 1) the outlet switch is also provided with three-stage current protection.
5. The fault self-healing method of a distribution line according to claim 1, wherein in step 3), the instantaneous residual voltage detection is started by losing voltage at one side, the acceleration transfer time is determined according to the residual voltage duration, and the contact switch is controlled to perform closing according to the acceleration transfer time.
6. A fault self-healing system for a distribution line, comprising a processor, wherein the processor is configured to execute instructions to implement the steps of:
1) Setting residual voltage time limit of sectional switch on distribution line: the closer to the power supply point, the shorter the residual voltage time limit;
2) When a certain section on the distribution line has a ground fault, a switch closest to the fault point in the switch upstream of the fault point trips to cut off the fault; the fault point upstream switch comprises a sectionalizing switch or an outgoing switch;
3) When the switch closest to the fault point in the upstream switch of the fault point trips, the downstream sectionalized switch loses voltage but keeps the closing position, and the instantaneous residual voltage detection is started; the switch closest to the fault point in the switch at the upstream of the fault point is subjected to split-phase reclosing; the instantaneous residual pressure detection is used for detecting the duration time of the instantaneous residual pressure;
when the fault is transient fault, the switch closest to the fault point in the upstream switch of the fault point is successfully reclosed, and the downstream switch recognizes that the transient residual voltage switching-off logic is not satisfied, so that the downstream switch still keeps on; if the duration of the instantaneous residual voltage reaches the residual voltage time limit, the instantaneous residual voltage brake-separating logic is satisfied, and if the duration of the instantaneous residual voltage is smaller than the residual voltage time limit, the instantaneous residual voltage brake-separating logic is not satisfied;
when the fault type is a permanent fault, the upstream switch delays to trip the coincident phase, the downstream switch detects instantaneous residual voltage at the moment, and the downstream switch nearest to the fault point executes opening and locking reverse closing; and the contact switch performs switching-on to finish power transfer of the downstream section of the fault area.
7. The fault self-healing system of the distribution line according to claim 6, wherein in the step 2), the tripping and fault removal of the switch closest to the fault point in the switch upstream of the fault point is realized by adopting current self-adaptive quick-break protection; the current self-adaptive quick-break protection comprises setting of over-current protection setting of an outgoing line switch and over-current protection setting of a sectionalizing switch, which are sequentially reduced.
8. The fault self-healing system of a distribution line according to claim 7, wherein the current adaptive quick-break protection further comprises: the self-adaptive setting is adopted to reconfigure the current quick-break protection of the sectionalizing switch so as to avoid the override trip of the sectionalizing switch.
9. The self-healing system of electrical distribution lines according to claim 8, wherein in step 1), the three-stage current protection is further configured for the outlet switch.
10. The fault self-healing system of the distribution line according to claim 6, wherein in the step 3), the instantaneous residual voltage detection is started by losing voltage at one side, the acceleration transfer time is determined according to the residual voltage duration, and the contact switch is controlled to perform closing according to the acceleration transfer time.
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